1. Field of the Invention
The present invention relates to a magnetic recording medium on which data can be magnetically recorded, and a magnetic recording device employing the same.
2. Related Background Art
Perpendicular magnetic recording system, which is capable of high density recording in comparison with conventional longitudinal magnetic recording system, is known as a recording system of a magnetic recording device such as a hard disk. In a magnetic recording medium compatible with the perpendicular magnetic recording, it has been attempted to employ magnetic recording layers such as Co/Pt and Co/Pd having high coercive force and a high squareness ratio as well as high perpendicular magnetic anisotropy. Use of these materials gives a recording magnetic film perpendicular magnetic anisotropy, which is high enough to overcome an increase in effects of thermal fluctuation. This increase accompanies finer recording bits caused by the shift toward high density.
For example, a magnetic recording medium achieving high coercive force and a high squareness ratio is known. In this magnetic recording medium, thickness and a thickness ratio of each layer are controlled in a multilayer film which is alternately formed by stacking magnetic layers such as Co and noble metal layers such as Pt. Alternatively, this multilayer film is additionally laminated with interposing nonmagnetic layers such as Ag.
Another magnetic recording medium is known, in which transition metal layers such as Co and noble metal layers such as Pt are alternately stacked on a foundation layer such as metal or oxide thin film and are heat-treated on the predetermined condition to achieve high coercive force and a high squareness ratio.
Still another magnetic recording medium having a multilayer is known. This multilayer film is alternately laminated with first layers and second layers. The first layers have platinum group layers such as Pt on either side of a transition metal layer such as Ag. A main ingredient of the second layers is Co.
Other magnetic recording media are also known: a magnetic recording medium in which a magnetic recording layer is formed by stacking a Co/Pd multilayer film on a single crystal MgO substrate; a magnetic recording medium in which a Co/Pd multilayer film is stacked on an approximately 30 nm-thick carbon foundation layer; and a magnetic recording medium in which a CoBO/PdBO multilayer film is stacked on a metal foundation layer having a face-centered cubic structure.